Atwood 7920-ll Screaming

Discussion in 'Heating / Cooling Systems' started by fredhead, Mar 9, 2020.

  1. fredhead

    fredhead Member

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    I've got an Atwood 7920 in my 2001 Coleman pup. It starts up fine, puts out good heat, but when I first start it, it screams, or squeaks. It sounds like the fan squealing, but I disassembled the unit and the fan isn't making the noise. Thing is, after a while of running the noise stopped Saturday.

    We have warm days forecast this week so I probably won't be able to run it again until the weekend. Any idea why I get this noise?
     
  2. Raycfe

    Raycfe Waterford Ct.

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    It 99.44% the motor. spray the shaft at both ends with wd40 and work the the shaft back and fourth.
     
  3. fredhead

    fredhead Member

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    An update, while it was squealing, I turned it off at the thermostat, which shut the burner off with the fan still running. The squealing stopped and the fan continued running until it cooled down and shut completely off. So I don't think it's the fan or motor.
     
  4. Spridle

    Spridle Well-Known Member

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    That does not make a lot of sense. They use a bronze bushing in them that simply wears out. I've had to replace the motor on both my pups for the squealing. Never came back. There's also a later style fan that's plastic, not metal. Much better balance and much quieter.
     
  5. rabird

    rabird Howdy!

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    regulator screams, or squeaks?

     
  6. fredhead

    fredhead Member

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    Update: I have run the heater a few times and the more I run it, the less noise it makes. It makes enough heat to run me out of the place!
     
  7. Raycfe

    Raycfe Waterford Ct.

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    You should still Lub the motor ....... it will help.
     
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  8. Sjm9911

    Sjm9911 Well-Known Member

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    Im in the if it moves ot needs lube camp.
     
  9. fredhead

    fredhead Member

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    I had given up on the furnace, but since I had nothing else to do, I pulled it out, took it apart, and sprayed PB Blaster down the motor shaft on both ends. Reassembled, reinstalled, and tested. No squealing!
    What confused me was it would squeal until the flame came on.
    I just have a habit of overthinking things.
     
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  10. WrkrBee

    WrkrBee Well-Known Member

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    The heat would make the shaft a little longer, or open the bushings a little more. It doesn't take much to change the running harmonic profile of equipment.
     
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